Determine if collection is of type IEnumerable<T>

Question

How to determine if object is of type IEnumerable <T>?

Code:

namespace NS {     class Program {         static IEnumerable<int> GetInts() {             yield return 1;         }         static void Main() {             var i = GetInts();             var type = i.GetType();             Console.WriteLine(type.ToString());         }     } } 

Output:

NS.1.Program+<GetInts>d__0 

If I change GetInts to return IList, everything is OK the output is:

 System.Collections.Generic.List`1[System.Int32] 

And this returns false:

namespace NS {     class Program {         static IEnumerable<int> GetInts() {             yield return 1;         }         static void Main() {             var i = GetInts();             var type = i.GetType();             Console.WriteLine(type.Equals(typeof(IEnumerable<int>)));         }     } } 

Answer 1

If you mean the collection, then just as:

var asEnumerable = i as IEnumerable<int>; if(asEnumerable != null) { ... } 

However, I'm assuming (from the example) that you have a Type:

The object will never be "of" type IEnumerable<int> - but it might implement it; I would expect that:

if(typeof(IEnumerable<int>).IsAssignableFrom(type)) {...} 

would do. If you don't know the T (int in the above), then check all the implemented interfaces:

static Type GetEnumerableType(Type type) {     if (type.IsInterface && type.GetGenericTypeDefinition() == typeof(IEnumerable<>))         return type.GetGenericArguments()[0];     foreach (Type intType in type.GetInterfaces()) {         if (intType.IsGenericType             && intType.GetGenericTypeDefinition() == typeof(IEnumerable<>)) {             return intType.GetGenericArguments()[0];         }     }     return null; } 

and call:

Type t = GetEnumerableType(type); 

if this is null, it isn't IEnumerable<T> for any T - otherwise check t.

Answer 2

Since IEnumerable<T> inherit IEnumerable (non generic) and if you don't need to know when a type is just IEnumerable and not IEnumerable<T> then you can use:

if (typeof(IEnumerable).IsAssignableFrom(srcType))